Grease compositions

ABSTRACT

1. A GREASE COMPOSITION COMPRISING AN OIL OF LUBRICATING VISCOSITY, AS A VEHICLE, AND A THICKENING AGENT COMPRISING A BORIC ACID COMPLEX OF ALKALINE EARTH METAL SALTS OF ALIPHATIC LONG CHAIN MONOCARBOXYLIC AND ALIPHATIC DICARBOXYLIC ACIDS.

United States Patent M 3,842,008 GREASE COMPOSITIONS Warner T. Car-man, Morrisville, Pa., assignor to Mobil Oil Corporation No Drawing. Filed May 18, 1973, Ser. No. 361,717

Int. Cl. C10m 5/16, 5/28, 7/52 US. Cl. 25218 ABSTRACT OF THE DISCLOSURE Grease compositions are provided comprising an oil of lubricating viscosity, as a vehicle, and a thickening agent comprising boric acid complexes of alkaline earth metal salts of aliphatic monocarboxylic and aliphatic dicarboxylic acids.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to grease compositions and relates more particularly to grease compositions having improved high temperature properties.

2. Description of the Prior Art The prior art has recognized that the ASTM dropping point of certain greases can be increased by about 70 to 100 F. through the use of hydroxystearate soaps. The prior art has also found that certain low molecular weight materials, such as boric acid, do not materially raise the dropping point of such greases. Furthermore, the prior art has also found that the dropping point of calcium greases can be increased by the addition of polycarboxylic acids as an ingredient of the grease fatty material (soap). Such addition has been found to raise the dropping point of the calcium grease by about 150 F. to a levelof about 350 F. Thus, for many applications where a dropping point of the order of about 450 F. to about 500 F. is desired, such greases fail to meet these high temperature requirements.

SUMMARY OF THE INVENTION In accordance with the present invention there are provided grease compositions having high temperature properties and comprising an oil of lubricating viscosity, as a vehicle, and a thickening agent comprising boric acid complexes of alkaline earth metal salts of 'monocarboxylic' and dicarboxylic acids. These greases, by virture of the combination of the aforementioned boric acid complexes of alkaline earth metal salts of monocarboxylic and dicarboxylic acids, as the thickening agent, have been found,

to exhibit increased ASTM dropping points of the order of 450-500" F. or higher.

In its more specific aspects, the thickening agent may be employed in any amount sufiicient to impart the desired consistency to the oil in forming a grease. In many applications the thickening agent is employed in an amount from about 2 to about 20%, and preferably from about 5 to about 15%, by weight, of the total grease composition. The salts of the monocarboxylic acid are, generally, employed in an amount from about 10 to about 90%, and preferably from about 60 to about 80%, by weight, of the total weight of the thickening agent.

20 Claims 3,842,008 Patented Oct. 15, 1974 The salts of the dicarboxylic acid are, generally, emp ployed in an amount from about 10 to about 90%, and preferably from about 20 to about by wegiht, of the total weight of the thickening agent. Boric acid is, in general, employed in an amount from about 5 to about 25%, by weight, of the total Weight of the thickening agent and from about 0.1 to about 5%, by weight, of the total weight of the grease. In this respect, substitution of boric anhydride for boric acid, was found to result in an unsatisfactory grease insofar as high temperature prop erties are concerned. The vehicle may comprise any oil of lubricating viscosity. Particularly preferred are mineral oils having a viscosity (SUS) of at least 40 seconds at 100 F., and preferably mineral oils having a viscosity within the range from about 60 to about 6,000 seconds at 100 F.

Representative of the monocarboxylic acids that can be employed for forming the corresponding alkaline earth metal salts are stearic acid, 12-hydroxystearic acid, palmitic acid, and l-auric acid. Representative of the dicarboxylic acids that can be employed for forming the corresponding alkaline earth metal salts are itaconic acid, adipic acid, azelaic acid and sebacic acid. In forming the alkaline earth metal salt for complexing with boric acid, the monocarboxylic or dicarboxylic acid is reacted with an alkaline earth metal oxide or hydroxide.

DESCRIPTION OF SPECIFIC EMBODIMENTS lowing formulation, which is typical of the improved greases, prepared in accordance with the present inven-' tion.

I I :Percent by weight Mineral Oil SUS at 100 F.) 84.05 12-Hydroxy Stearic Acid 9.97 Sebacic Acid 3.52 Boric Acid .26 Calcium Hydroxide 2.20

The above grease composition was prepared in the conventional manner in an open'grease kettle by saponifying the fatty material in a portion of the mineral oil to a temperature between about 220 F. and about 250 F.- to form the corresponding soap. After the grease had bodied-up, the boric acid was added and the temperature was slowly increased to 350 F. to produce a homogeneous complexed product. After cooling the grease to 250 F., the remaining portion of the mineral oil was added and the grease was then homogenized once through a homogenizer at a .004" setting. The resulting grease exhibited an unworked penetration at 77 F. of 225 mm./10. The ASTM D2265 dropping point was 456 F. Formulations prepared in accordance with the manner described above are set forth in the following table in which both composition and characteristics are also disclosed.

TABLE Examnlo 1 2 3 4 5 6 7 8 9 10 11 12 Composition:

Mineral oil (100 S US at 100 F.) 85.86 87. 43 92. 35 80. 49 84. 70 84. 64 84. 84 84. 64 84.05 86. 56 80.86 85.41 Calcium hydroxide 2. 14 2. 34 4. 67 5. 31 2. 30 2. 35 2. 35 2. 35 2. 1. 82 2. 64 3. 43 Bone and .23 .50 .26 .23 .38 .32 Stearic acid 2. 98 8. 76 Hydroxystearieacid 12. 00 10. 00 9. 75 9. 75 9. 80 9. 75 9. 97 8. 54 11. 96 8. 16 Dicarboxyho acids:

Itamnic 3. Adi 3. 25 2.68

..-5 .3. 01 3.52 2.85 Bench test results: "nun-'- n 4' l6 Penetrations at 77 F.:

Unwnrkorl 230 233 249 259 240 304 273 295 225 312 273 295 Worked, 60 tmles 235 2 9 277 235 305 277 300 816 276 294 Dropping po1nt, F. ASTM D-2265 426 331 323 335 456 367 465 500 s iiaiiii'drnm two phases at about 270-275 F.

! Separated into two phases at about 225230 F.

4 Separated into two phases at about 312 F.

Referring to the above table it will be noted that Examples 1 and 3 disclose that a grease formulated from calcium stearate or calcium hydroxystearate separates into two phases when heated to temperatures of the order of 25 225-275 F. Incorporating a dicarboxylic acid, e.g., itaconic, adipic, azelaic or sebacic acid as part of the fatty material, as shown in Examples 5, 6, 7 and 8 will increase their thermal stability as measured by their dropping point. As shown in Example 2, incorporating boric acid into a conventional calcium/hydroxystearate grease does not improve its thermal stability.

' In contrast, however, the calcium soaps of a combination of monocarboxylic and dicarboxylic acids and boric acid; as disclosed in Examples 4, 9, 10, 11 and 12, resulted in greases having much greater thermal stability than was previously obtained.

While this invention has been described with reference to preferred compositions and components therefor, it will be understood, by those skilled in the art, that de- 40 partures from the preferred embodiments can be effectively made and are within the scope of the specification.

I claim:

1. A grease composition comprising an oil of lubricating viscosity, as a vehicle, and a thickening agent comprising a boric acid complex of alkaline earth metal salts of aliphatic long chain monocarboxylic and aliphatic dicarboxylic acids.

2. A grease as defined in Claim 1 wherein said thickening agent is present in an amount from about 2 to about 20% by weight.

3. A grease as defined in Claim 1 wherein said thickening agent is present in an amount from about 5 to about 15%,by weight.

4. A grease as defined in Claim 1 wherein said salt of the monocarboxylic acid is present in an amount from about 10 to about 90%, by weight, of said thickening agent. 7

p 5. A grease as defined in Claim 1 wherein said salt of the monocarboxylic acid is present in an amount from about 60 to about by weight, of said thickening agent. 1

6. A grease as defined in Claim 1 wherein said salt of the dicarboxylic acid is present in an amount from about 10 to about by weight, of said thickening agent.

8. A grease as defined in Claim 1 wherein boric acid is present in an amount from about 5 to about 25%, by weight, of said thickening agent.

9. A grease as defined in Claim 1 wherein boric acid is present in an amount from about 0.1 to about 5%, by weight, of the total weight of the grease.

10. A grease as defined in Claim 1 wherein the vehicle comprises a mineral oil. 7 I I 11. A grease as defined in Claim 1 wherein the vehicle comprises a mineral oil having a viscosity (SUS) of at least 40 seconds at F.

12. A grease as defined in Claim 1 wherein the vehicle is a mineral oil having a viscosity (SUS) within the range from about 60 to about 6,000 seconds at 100 F.

13. A grease as defined in Claim 1 wherein the monocarboxylic acid is stearic acid.

14. A grease as defined in Claim 1 wherein the monocarboxylic acid is 12-hydroxystearic acid.

15. A grease as defined in Claim 1 wherein the monocarboxylic acid is palmitic acid.

16. A grease as defined in Claim 1 wherein the monocarboxylic acid is lauric acid.

17. A grease as defined in Claim 1 wherein the dicarboxylic acid is itaconic acid.

18. A grease as defined in Claim 1 wherein the dicarboxylic acid is adipic acid.

19. A grease as defined in Claim 1 wherein the die boxylic acid is azelaic acid.

20. A grease as defined in Claim 1 wherein the dicarboxylic acid is sebacic acid.

7 References Cited UNITED STATES PATENTS 2,607,935 8/1952 Sproule et a1 252-18 2,987,476 6/1961 Hartley et al 2s21s 3,103,491 9/1963 Wright 252 25 PATRICK P. GARVIN, Primary Examiner I. VAUGHN, Assistant Examiner US. Cl. X.R. 252-25 

1. A GREASE COMPOSITION COMPRISING AN OIL OF LUBRICATING VISCOSITY, AS A VEHICLE, AND A THICKENING AGENT COMPRISING A BORIC ACID COMPLEX OF ALKALINE EARTH METAL SALTS OF ALIPHATIC LONG CHAIN MONOCARBOXYLIC AND ALIPHATIC DICARBOXYLIC ACIDS. 